Chemical containers, such as portable fuel canisters or jugs, are typically stored in or around homes or businesses for applications in which relatively small quantities of chemicals (e.g., liquid fuels) are used. Such applications may include, for example, vehicles including watercraft, automobiles, snowmobiles, motorcycles, all-terrain vehicles and the like, and/or yard maintenance equipment, including lawnmowers, snow blowers, leaf blowers, chain saws, and the like. Typical fuel containers are vented and/or do not seal well against the venting of gaseous vapors from inside the container, which can lead to contamination of a confined storage area, or of a transport vehicle's ambient air and/or upholstery, with unpleasant and potentially harmful fumes or vapors. This can be particularly problematic on relatively warm days when heat can raise the vapor pressure inside of the container, forcing more vapors out of the container.